Two-stage hydrocracking-hydrotreating process to make lube oil

ABSTRACT

A high-viscosity-index mineral lubricating oil is produced by treating, for instance, a deasphalted residuum or a raw, heavy lubricating distillate oil in a two-stage process. The feedstock is first catalytically hydrocracked, then catalytically hydrogenated and can be fractionated and dewaxed to produce a finished product. Catalysts such as nickel-tungstate on boriaalumina and nickel-molybdate on alumina are employed in the two stages, respectively. The catalysts are preferably used in sulfided form.

United States Patent Divijak, Jr. et al.

[ Feb. 15,1972

[22] Filed:

[54] TWO-STAGE HYDROCRACKING- HYDROTREATING PROCESS TO MAKE LUBE OIL[72] inventors: Joseph M. Diviiak, Jr., Grifiith, lnd.; Maurice K.Rausch, South Holland, [11.

Atlantic Richfield Company, New York, N.Y.

Sept. 5, 1969 [21] Appl.No.: 855,737

[73] Assignee:

52] U.S.Cl ..260/s8,208/57,2o8/s8, 208/87, 208/144, 252/432 511 Int. Cl...Cl0g23/02,Cl0g13/06,Cl0g 37/00 [58] FieldoiSearch..208/l8,58,59,111,143,144, 208/87 [56] References Cited UNITED STATESPATENTS 2,779,713 1/1957 Coleetal ..208/57 2,917,448 12/1959 Bewtheretal ..208/57 3,506,565 4/1970 White eta]. ....208/58 3,444,071 5/1969Van ZijllLanghout ..208/59 Primary Examiner -Delbert E. Gantz AssistantExaminer-G. E. Schmitkons AttorneyMcLean, Morton & Boustead [57]ABSTRACT 12-Claims, No Drawings tion of high quality mineral lubricatingoils from feedstocks that are not normally used in present commercialprocesses to make such products. In addition to mineral lube oildistillates and deasphalted residuums of relatively high quality, stockscontaining high percentages of sulfur, nitrogen and carbon residue, suchas sour oils and more highly contaminated deasphalted oils, may beemployed as feeds. Moreover, a wide range of products is possible.Lubricating oils with viscosity indexes up to about 150 or more (ASTMDesignation: D-2270) with partial or even complete aromatic saturationare possible. The present process is also more economical than presentmethods for the production of high viscosity index oils involv- ,ingsolvent treatment, dewaxing and finishing. The invention produces suchoils by hydrocracking the mineral oil feed while in contact with acatalyst containing nickel, and tungsten or molybdenum along with boriaon an alumina support, followed by hydrogenation of resultinghydrocracked materials of lubricating viscosity over a hydrogenationcatalyst whereby a high viscosity index oil is produced.

Many of the present day refining techniques employed to produce highquality mineral lubricating oils having high viscosity indexes possesscertain undesirable features. For example, the production of finishedoils having a viscosity index of 95 by known methods of fractionationand solvent extraction of vacuum distillates or deasphalted residuumsfollowed by dewaxing and finishing with acid, clay or hydrogen, normallyresults in yields of about 50 to 65 volume percent. The presentinvention, however, can produce 95 VI oils in yields of about 60 to 80volume percent on a dewaxed basis and yields of about 40 volume percentor more on a dewaxed basis of oils having viscosity indexes of about 120and higher.

The mineral lubricating oils treated by the process of the presentinvention are of lubricating viscosity at 210 F. and are principallystocks having at least about 90 weight percent boiling above about 600F.; preferably the feed is a residuum at least about 90 weight percentof which boils above about 1,000 F. The feeds are usually oils of atleast about 50 V1, e.g., about 50 to 80, or even about 70 to 80 V1, andcan be derived from paraffinic or mixed base crude oils. The total orfull range oil of lubricating viscosity obtained by the method ofthepresent invention has a viscosity index in the range of at leastabout 90, say up to about 150 or more, with the increase in theviscosity index of the product being at least about 20, preferably atleast about 30, over that of the feed. Both the initialhydrocarbonfeedstock and the product of lubricating viscosity from thehydrogenation reaction boil over a considerable temperature range, e.g.,overa range of at least about 100 F., often at least about 200 F. Thehydrocarbon feedstock preferably has a specific dispersion (ASTMDesignation: D-l218) in the range of about 105-165 while the specificdispersion of the product of lubricating viscosity is preferably in therange of about 100-1 10. The method of the present invention isparticularly suitable for treating feedstocks having a specificdispersion in the range of about 135-165, such stocks being the highlycontaminated stocks,

containing larger amounts of aromatics and frequently having beensubjected only to fractionation and deasphalting. Thus the presentmethod can utilize these economically cheaper feedstocks to produce highquality lubricating oils in high yields.

Hydrocracking of the feedstock which includes ring opening and usuallydesulfurization and denitrogenation, is carried out in contact with acatalyst containing nickel and one or both of molybdenum or tungstensupported, along with boria, on a catalytically active alumina base. Themetals of the catalyst may be present in the form of free metals or incombined form such as the oxides and sulfides, the sulfides being thepreferred form. Examples of such mixtures or compounds are nickelmolybdate or tungstate (or thiomolybdate or thiotungstate). Thesecatalytic ingredients, along with boria, are employed while disposed ona catalytically-active alumina.

The catalyst is composed of minor, catalytically effective amounts ofnickel, tungsten and/or molybdenum and boria on the alumina base. Nickelmay often comprise about l-40 weight percent of the catalyst, preferablyabout 2-10 percent, with the total amount of tungsten and molybdenumbeing about 5-30 weight percent, preferably about 10-20 percent, of thecatalyst on a metal oxide basis. Preferably the boria is present in anamount of about 2 to 10 weight percent, based on the total weight of thecatalyst while the alumina is the major component of the catalyst, e.g.,the essential balance of the composition.

The catalyst composition used in the hydrocracking stage of the presentinvention can be prepared by adding the nickel, tungsten, molybdenum andboria components to the alumina by the various methods known to the art,for example by impregnation or precipitation and coprecipitation usingsuitable compounds of the metals and boron. For example, aluminaparticles containing boria or a material which upon heating yieldsboria, can be mixed with aqueous ammonia solutions containing nickel andtungsten, and/or molybdenum, or other aqueous solutions of water-solublecompounds of nickel and tungsten and/or molybdenum, so that the metalcomponents are absorbed on the base. Alternatively, the promotingmaterials can be precipitated on the boria-containing alumina basethrough suitable reaction of an aqueous slurry of the support containingwater-insoluble salts of the promoting metals. The boria-containingparticles can be formed into macrosize either before or after beingmixed with the nickel and tungsten and/or molybdenum components. Thecatalyst can be dried and calcined, e.g., at temperatures of about 800to 1,200 F. or somewhat more. Prior to use the catalyst is preferablysulfided at elevated temperature.

The hydrocracking step is carried out under conditions designed toselectively crack the feed so that opening of aromatic and naphthenicrings is favored, rather than the splitting of chains into lowermolecular weight compounds. Such conditions include a temperature ofabout 725to 875 F., preferably about 750to 850 F. The other reactionconditions often include a hydrogen partial pressure of about 1,000 to5,000 p.s.i.g., preferably about 1,500 to 3,000 p.s.i.g. In theproduction of VI oils by the method of this invention, cracking may takeplace to the extent that from about 5 to 10 percent by volume of theproduct of the hydrocracking stage is material boiling below about 600F. In the production of VI oils, about 30 to 40 percent by volume of theproduct of the hydrocracking stage may be comprised of such materials.The amount of free hydrogen employed during hydrocracking can begenerally about 1,000 to 5,000 standard cubic feet per barrel ofhydrocarbon feed,,preferably about 1,500 to 3,000 standard cubic feetper barrel. The weight hourly space velocity (WHSV), weight units offeed in'-. troduced into the reaction zone per weight unit of catalystper hour, will often be in the range of about 0.3 to 3, preferably about0.5 to 2. The reactor effluent from the first or hydrocracking stage canbe flashed to prevent hydrogen sul tide and ammonia from going to thehydrogenation stage, but this is not necessary, especially ifnonprecious metal hydrogenation catalysts are used in the hydrogenationstage. Also, if desired any light hydrocarbons can be removed from thefeed to the hydrogenation stage.

Lubricating oil from the hydrocracking stage is subjected to ahydrogenation operation which involves contacting lubricating oil,preferably the essentially full range lube oil, from the hydrocrackingstage in the presence of hydrogen with a solid hydrogenation catalyst ata temperature of about 550to 825 F., preferably about 600 to 800 F. Itis preferred that the temperature employed in the second stage he atleast about 50 F. less than the temperature of the first stage foroptimum decolorization and saturation. The other reactionconditionsoften include pressures of about 1,000 to 5,000 p.s.i.g., preferablyabout 1,500 to 3,000 p.s.i.g.; space velocities (WHSV) of about 0.3 to5, preferably about 0.5 to 3; and

molecular hydrogen to feed ratios of about500 to 3,500 standard cubicfeet of hydrogen per barrel of hydrocarbon feed, preferably about 1,500to 2,500 standard cubic feet of hydrogen per barrel of hydrocarbon feed.

The solid catalyst employed in the hydrogenation operation is preferablya sulfur-resistant, nonprecious metal hydrogenation catalyst, such asthose conventionally employed in the hydrogenation of heavy petroleumoils. Examples of suitable catalytic ingredients are tin, vanadium,members of Group VIB in the periodic table, i.e., chromium, molybdenumand tungsten and metals of the iron group, i.e., iron, cobalt andnickel. These metals are present in minor, catalytically effectiveamounts, for instances, about 2 to 30 weight percent of the catalyst,and may be present in the elemental form or in combined form such as theoxides or sulfides, the sulfide form being preferred. Mixtures of thesematerials or compounds of two or more of the oxides or sulfides can beemployed, for example, mixtures or compounds of the iron group metaloxides or sulfides with the oxides or sulfides of Group VIB constitutevery satisfactory catalysts. Examples of such mixtures or compounds arenickel molybdate, tungstate or chromate (or thiomolybdate,thio-tungstate or thiochromate) or mixtures of nickel or cobalt oxideswith molybdenum, tungsten or chromium oxides. As the art is aware and asthe specific examples below illustrate, these catalytic ingredients aregenerally employed while disposed upon a suitable carrier of the solidoxide refractory type, e.g., a predominantly calcined or activatedalumina. To avoid undue cracking the catalyst base and other componentshave little, if any, hydrocarbon cracking activity. Usually not morethan about 5 volume percent, preferably not more than about 2 volumepercent, of the feed is cracked in the second or hydrogenation stage toproduce materials boiling below about 600 F. Commonly employed catalystshave about 1 to weight percent of an iron group metal and about 5 to 25percent ofa Group VIB metal (calculated as the oxide). Advantageously,the catalyst is nickel molybdate or cobalt molybdate, supported onalumina. Such preferred catalysts can be prepared by the methoddescribed in US. Pat. No. 2,938,002.

Other suitable hydrogenation catalysts which can be employed in themethod of this invention include the platinum group metal types. Suchcatalysts often have a minor catalytically effective amount, say about0.05 to 2 weight percent, preferably about 0.1 to 1 weight percent ofone or more platinum group metals carried on a solid support, especiallyan active alumina. Suitable platinum group metals include platinum,rhodium and ruthenium with platinum being preferred.

The catalysts employed in both the hydrocracking and hydrogenationstages of the method of this invention are preferably disposed in thereaction zones as fixed beds. Such fixed bed catalysts are usuallyparticles of macrosize, e.g., about one sixty-fourth to one-fourth inch,preferably about one-sixteenth to one-eighth inch, in diameter, and,about one sixty-fourth to 1 inch or more, preferably about one-eighth toone-half inch in length. These catalysts can be made by extrusion,tableting or other suitable procedures.

The hydrogenation operation provides additional aromatic saturation,color improvement and stability towards oxidation and corrosion.Additional color improvement can be provided by subjecting the effluentfrom the hydrogenation operation to treatment with ultraviolet light.The treatment was found to lighten considerably the color of the darkeroils, a surprising result since such treatment usually produces theopposite effect. The reactor effluent from the hydrogenation stage maybe flashed to recover hydrogen for possible recycle and fed to a steamstripper to remove excess light hydrogenated components. The oil canthen be fractionated and the lube fractions dewaxed. This dewaxing stepcan be carried out, for example, by pressing or by solvent dewaxingusing methyl ethyl ketone and toluene as the solvent system. Dewaxingmay be carried out prior to the initial hydrocracking step but it ispreferred to conduct dewaxing after hydrogenation has been completed. Noadditional finishing is required. Yields of about 60 to volume percent,based on the raw stock, of V1 oils are not uncommon and finished baseoils having viscosity indexes of and higher are obtained in economicalyields, e. g., in the range of about 40 volume percent and higher.

The following example is illustrative of the method of this invention:

Deasphalted petroleum residuum was fed to an isothermal reactor unithaving a nickel-tungstate on boria-aluminia catalyst in the first orhydrocracking stage and nickel-molybdate on alumina catalyst in thesecond or hydrogenation stage. The catalysts were macrosize andpresulfided. The feedstock employed had the following specifications:

Vl (D-2270) (dewaxed basis) 76 Gravity, AP1 23.1

' Flash, F. 555

Viscosity, SUS/210F. 154.4 Pour, F. 1 20+ ASTM color Dark Carbon residue(Con.), wt.% 1.58 10% boiling point 1,000F.

Table I lists operating conditions and dewaxed oil inspections fornominal 100 and V1 operations.

The catalysts employed in the successive stages analyzed as follows:

TABLE 11 NiW on NiMo on Boria-Alumina Alumina Nickel, wt.% 5.35 2.30Tungsten Oxide, wt.% 12.15 Molybdenum Oxide, wt.% 15.60 Silicon Dioxide,wt.% 0.29 Boria, wt.% 5.06 Volatile matter at 1,200 F. 3.95 (at 1,000F.) 0.86 Apparent Density, g./rn1. 0.75 0.765

It is claimed:

1. A process of preparing a mineral hydrocarbon lubricating oil having aviscosity index of at least about 90 on a dewaxed basis which comprises:

a. Contacting a mineral hydrocarbon oil feedstock of lubricatingviscosity at 210 F., at least about 90 weight percent of which boilsabove about 600 F. and having a viscosity index of about 50 to 80, withmolecular hydrogen under hydrocracking conditions including atemperature of about 725 to 875 F., in the presence of a catalyst havingminor, catalytically effective amounts of each of nickel, a memberselected from the group consisting of tungsten and molybdenum, and boriaon an active alumina support; and

b. Contacting hydrocarbon oil of lubricating viscosity from step (a)with molecular hydrogen under hydrogenation conditions including atemperature of about 550 to 825 F. in the presence of a solidhydrogenation catalyst at a hydrotreating severity such that not morethan about 5 volume percent of the feed to step (b) boiling above 600 F.is cracked to material boiling below about 600 F. to produce oil oflubricating viscosity having a viscosity index of at least about 90 andat least about 20 viscosity index number greater than the hydrocarbonoil feedstock passing to step (a).

2. The process of claim 1 wherein said hydrocracking conditions includea hydrogen partial pressure of about 1,000 to 5,000 p.s.i.g., a weighthourly space velocity of about 0.3 to 3 WHSV and a molecular hydrogen tohydrocarbon feed ratio of about 1 ,000 to 5,000 standard cubic feet perbarrel of feed.

3. The process of claim 2 wherein the catalysts are in sulfide form.

4. The process of claim 3 wherein the hydrocracking catalyst containsabout 2 to 10 weight percent nickel, about 10 to 20 percent of themember selected from the group consisting of tungsten and molybdenum onan oxide basis, and about 2 to 10 percent boria.

5. The process of claim 4 wherein the selected member of the catalystemployed in the hydrocracking stage is tungsten.

6. The process of claim 2 wherein said hydrogenation conditions includea temperature of about 550to 825 F., a hydrogen partial pressure ofabout 1,000 to 5,000 p.s.i.g., a weight hourly space velocity of about0.3 to 5 WHSV and a molecular hydrogen to hydrocarbon feed ratio ofabout 500 to 3,500 standard cubic feet per barrel of feed.

7. The process of claim 6 wherein the catalyst employed in thehydrogenation stage contains minor, catalytically-effective amounts of amember selected from the group consisting of nickel and cobalt, andmolybdenum on alumina.

8. The process of claim 7 wherein the catalyst is in sulfide form.

9. The process of claim 8 wherein the hydrocracking catalyst containsabout 2 to l weight percent nickel, about 10 to 20 percent of the memberselected from the group consisting of tungsten and molybdenum on anoxide basis, and about 2 to 10 percent boria.

10. A process of preparing a mineral hydrocarbon lubricating oil havinga viscosity index of at least about on a dewaxed basis which comprises:

a. Contacting a mineral hydrocarbon oil feedstock of lubricatingviscosity at 210 F., at least 90 weight percent of which boils aboveabout l,000 F. and having a viscosity index of about 50 to 80, withmolecular hydrogen under hydrocracking conditions including atemperature of about 750 to 850 F., a hydrogen partial pressureof about1,500 to 3,000 p.s.i.g., a weight hourly space velocity of about 0.5 to2 WHSV and a molecular hydrogen to hydrocarbon feed ratio of about 1,500to 3,000 standard cubic feet per barrel of feed, in the presence of acatalyst containing about 2 to 10 weight percent nickel, about 10 to 20percent tungsten on an oxide basis and about 2 to 10 percent boria on anactive alumina support, the metals of the catalyst being present in thesulfide form; and Contacting hydrocarbon oil of lubricating viscosityfrom step (a) with molecular hydrogen under hydrogenation conditions,including a temperature of about 600 to 800 F., a hydrogen partialpressure of about 1,500 to 3,000 p.s.i.g., a weight hourly spacevelocity of about 0.5 to 3 WHSV and a molecular hydrogen to hydrocarbonfeed ratio of about 1,500 to 2,500 standard cubic feet per barrel offeed in the presence of a solid hydrogenation catalyst containing minor,catalytically effective amounts of a member selected from the groupconsisting of nickel and cobalt, and molybdenum on alumina, the metalsof the catalyst being present in the sulfide form, to produce oil oflubricating viscosity having a viscosity index of at least about 90 andat least about 30 viscosity index numbers greater than the hydrocarbonoil feedstock passing to step (a).

11. The process of claim 1 wherein the product from step (b) isfractionated to separate oil of lubricating viscosity and thelubricating oil fraction is dewaxed.

12. The process of claim 10 wherein the product from step (b) isfractionated to separate oil of lubricating viscosity and thelubricating oil fraction is dewaxed.

2. The process of claim 1 wherein said hydrocracking conditions includea hydrogen partial pressure of about 1,000 to 5,000 p.s.i.g., a weighthOurly space velocity of about 0.3 to 3 WHSV and a molecular hydrogen tohydrocarbon feed ratio of about 1,000 to 5,000 standard cubic feet perbarrel of feed.
 3. The process of claim 2 wherein the catalysts are insulfide form.
 4. The process of claim 3 wherein the hydrocrackingcatalyst contains about 2 to 10 weight percent nickel, about 10 to 20percent of the member selected from the group consisting of tungsten andmolybdenum on an oxide basis, and about 2 to 10 percent boria.
 5. Theprocess of claim 4 wherein the selected member of the catalyst employedin the hydrocracking stage is tungsten.
 6. The process of claim 2wherein said hydrogenation conditions include a temperature of about550*to 825* F., a hydrogen partial pressure of about 1,000 to 5,000p.s.i.g., a weight hourly space velocity of about 0.3 to 5 WHSV and amolecular hydrogen to hydrocarbon feed ratio of about 500 to 3,500standard cubic feet per barrel of feed.
 7. The process of claim 6wherein the catalyst employed in the hydrogenation stage contains minor,catalytically-effective amounts of a member selected from the groupconsisting of nickel and cobalt, and molybdenum on alumina.
 8. Theprocess of claim 7 wherein the catalyst is in sulfide form.
 9. Theprocess of claim 8 wherein the hydrocracking catalyst contains about 2to 10 weight percent nickel, about 10 to 20 percent of the memberselected from the group consisting of tungsten and molybdenum on anoxide basis, and about 2 to 10 percent boria.
 10. A process of preparinga mineral hydrocarbon lubricating oil having a viscosity index of atleast about 90 on a dewaxed basis which comprises: a. Contacting amineral hydrocarbon oil feedstock of lubricating viscosity at 210* F.,at least 90 weight percent of which boils above about 1,000* F. andhaving a viscosity index of about 50 to 80, with molecular hydrogenunder hydrocracking conditions including a temperature of about 750* to850* F., a hydrogen partial pressure of about 1,500 to 3,000 p.s.i.g., aweight hourly space velocity of about 0.5 to 2 WHSV and a molecularhydrogen to hydrocarbon feed ratio of about 1,500 to 3,000 standardcubic feet per barrel of feed, in the presence of a catalyst containingabout 2 to 10 weight percent nickel, about 10 to 20 percent tungsten onan oxide basis and about 2 to 10 percent boria on an active aluminasupport, the metals of the catalyst being present in the sulfide form;and b. Contacting hydrocarbon oil of lubricating viscosity from step (a)with molecular hydrogen under hydrogenation conditions, including atemperature of about 600* to 800* F., a hydrogen partial pressure ofabout 1,500 to 3,000 p.s.i.g., a weight hourly space velocity of about0.5 to 3 WHSV and a molecular hydrogen to hydrocarbon feed ratio ofabout 1,500 to 2,500 standard cubic feet per barrel of feed in thepresence of a solid hydrogenation catalyst containing minor,catalytically effective amounts of a member selected from the groupconsisting of nickel and cobalt, and molybdenum on alumina, the metalsof the catalyst being present in the sulfide form, to produce oil oflubricating viscosity having a viscosity index of at least about 90 andat least about 30 viscosity index numbers greater than the hydrocarbonoil feedstock passing to step (a).
 11. The process of claim 1 whereinthe product from step (b) is fractionated to separate oil of lubricatingviscosity and the lubricating oil fraction is dewaxed.
 12. The processof claim 10 wherein the product from step (b) is fractionated toseparate oil of lubricating viscosity and the lubricating oil fractionis dewaxed.